ZETA (ζ) CANCRI
MULTIPLE STAR
Right Ascension:
8h 12m 12.6s
Best Seen:
1/15 - 5/1
Declination:
17º 38' 52"
Combined
Magnitude:
4.67
Computer File:
zetacnc
Constellation:
Cancer
Apparent
Separation:
9.00"
Actual
Compared to
Distance
83 l.y.
--
Separation
1.8 billion and 16.3 billion miles
19 and 175 Earth/Sun
Orbital Period
varies - see below
--
Actual Brightness
--
2.8 / 1.9 / 1.7 (Sun)
Magnitude
5.68 / 6.09 / 6.22
--
Mass
varies - see below
--
Surface Gravity
--
--
Surface Composition (by mass)
74% hydrogen 24% helium 2% everything else
same (Sun)
Spectral Type
F8V / F9V / G5V
G2 V (Sun)
Density (gram/cubic cm)
--
--
WHAT TO LOOK FOR THROUGH THE TELESCOPE:
-
Recommended eyepiece: 24mm or 40 mm.
-
When people look through the telescope they should see two stars next to each other, with a third star close by. One star may be slightly dimmer than the others.
ZETA CANCRI INFORMATION:
- The two stars next to each other can be called Star A and Star B.
a. Stars A and B are separated by 0.8 arcseconds.
b. A and B take about 60 years to orbit each other, and are about 19 AU’s apart.
c. Star A’s mass is 1.11 times that of our sun. Star B’s mass is the same as our sun.
- The third star can be called Star C.
a. AB and C take about 1100 years to orbit each other.
b. Star C’s mass is estimated to be about 0.99 times that of our sun.
- A fourth, unseen star orbits Star C. This unseen star can be called Star D.
a. Star D’s existence was suggested for years based on Star C’s motion. The Canada-France-Hawaii Telescope was the first to take a picture of D, with the help of adaptive optics. The European Southern Observatory’s observations confirmed its existence.
b. Stars C and D are separated by 0.3 arcseconds.
c. D orbits C in about 17 years.
d. Star D’s mass is about 0.93 times that of our sun.
- Interesting stuff
a. The Canada-France-Hawaii Telescope’s observations indicate that Star D may really be a multiple system consisting of two low mass, very red M dwarfs. The European Southern Observatory’s observation strengthen that argument.
b. The ESO may have even detected another star, called Star E, orbiting even closer to Star C than Star D.
c. For both of these possibilities, more time and data are needed to know for sure.
Item
Updated
Notes
Coordinates
11-13-2002
OK - file created today – Scott’s The Flamsteed Collection and SIMBAD
Combined Magnitude
11-13-2002
OK - file created today – Flamsteed
Apparent Separation
11-13-2002
OK - file created today – Flamsteed
Distance
11-13-2002
OK - file created today – in agreement with Flamsteed and SIMBAD
Separation
11-13-2002
OK - file created today – http://www.sciencenet.org.uk/astron/const/Cancer/zetacan.html
Orbital Period
11-22-2002
see other information
Actual Brightness
11-13-2002
OK - file created today – Flamsteed
Magnitude
11-13-2002
OK - file created today – Flamsteed
Mass
11-22-2002
see other information
Surface Gravity
Surface Composition
OK for all stars
Spectral Type
11-18-2002
Flamsteed says star C is the F9 star, but SIMBAD and other web searches give info here
Density
Other Information
11-13-2002
info from http://www.eso.org/~arichich/publications/2000a_a...364..225.pdf and http://www.cfht.hawaii.edu/Science/Astros/Imageofweek/ciw010500.html and
http://www.sciencenet.org.uk/astron/const/Cancer/zetacan.html